Did you catch a knowing feeling that when the high priestess melded with Spock that she accessed his memory and saw things--the flashes of scenes on the Enterprise? That might have been what caused her to tell Spock "what you seek is elsewhere."

Somehow, it seems to be similar to after having done all the gallons of coffee, the all-nighters, and tears you come to graduation but do not accept the degree. Spock did the work and developed the discipline all those years. He still indeed is Kolinahru. He achieved Masters. He had to have already prepared to leave his emotional ties behind. One last step. One step; one breath away Spock woke to himself. He with awareness rejected the (diploma) award and with it the status and a life path that would have taken him away from what he really cared about. He could not deny that call. James called to him from deep space. James and "The Lady" called--their true love. It's a parallel to that scene when Spock after being accepted into the Vulcan Science Academy turned on his heel and went to Starfleet instead (to his father's horror and chagrin). Two places Spock made choices that changed his life.